In a process of manufacturing a semiconductor device, an Atomic Layer Deposition (ALD) method and a Molecular Layer Deposition (MLD) method is used to form a film containing metal on a surface of a semiconductor wafer (hereinafter). The ALD method includes alternately supplying a source gas containing metal and a reactant gas reacting with the source gas to a wafer on which a film is to be formed, and depositing the metal on the surface of the wafer to form a metal film. The MLD method includes forming a film of a compound containing metal. Hereinafter, in the present application, the ALD method and the MLD process will be collectively referred to as an “ALD process”.
For example, a plasma ALD method has been used which facilitates action of a source gas (a first process material) with a plasmarized reactant gas (a second process material).
The ALD method is a film forming method which is capable of forming a film on the surface of a wafer having a stereoscopic structure at a more uniform thickness, thus providing good step coverage. Therefore, the present inventors of the present disclosure have examined, for example, the use of a plasma ALD method as a method for forming a metal film such as a Ti film inside a contact hole formed in an insulation layer.
Further, the present inventors focused on the surface roughness of a film (hereinafter, referred to as “roughness”) as an indicator for determining whether an electrical characteristic of a film obtained using the plasma ALD method is good or bad.
In addition, a resistance element manufacturing technology has been used to form a first resistance layer of tantalum nitride (TaN) by a thermal Atomic Layer Deposition (thermal ALD) method, followed by forming a second resistance layer of TaN by a plasma ALD method. However, this technology does not disclose a method for forming a film while focusing on the improvement of roughness.